Bitter.Core系列九：Bitter ORM NETCORE ORM 全网最粗暴简单易用高性能的 NETCore 之 WITH 子句支持

有时我们在聚合查询中，经常会有复杂的聚联查询。有时表的聚联查询SQL 子句比较复杂，DBA 会经常告诉们，能否通过WITH 子句优化。WITH 子句，是对SQL 聚联查询的优化。Bitter.Core 支持对MSSQL WITH 子句的支持。示例代码如下：

示例DEMO:

public static List<TScoreSearchDto> With_Page_Demo(int type, string studentname)
        {
            #region //聚联条件分页查询  年级的LEFT JOIN 子语句 使用WITH 来替代

            var withsql = @"WITH grade as(select* from t_Grade where fid=@id)"; //定义WITH 子句
            var sql = @"SELECT   score.FScore,student.FName  as studentName,class.FName as className,grade.FName as  gradeName FROM  dbo.t_StudentScore score
            LEFT JOIN dbo.t_student student  ON score.FStudentId = student.FID
            LEFT JOIN dbo.t_class class ON  student.FClassId=class.FID
            LEFT JOIN grade ON grade.FID=class.FGradeId";

            PageQuery pq = new PageQuery(sql, null);
            pq.AddPreWith(withsql, new { id = 3 });

            pq.Where("1=1");

            if (type == 1)
            {
                pq.Where("score.FScore>60 ");
            }
            if (type == 2)
            {
                pq.Where("score.FScore>60 and score.FScore<80 ");
            }
            if (!string.IsNullOrEmpty(studentname))
            {
                pq.Where(" student.FName like '%' + @FScoreName + '%'", new { FScoreName = studentname });
            }

            //通过ThenAsc 方法指定字段排序
            pq.ThenASC("score.FScore ");

            //通过ThenDESC 方法指定字段排序
            pq.ThenDESC("student.FName");

            //自己直接指定排序字段和排序关键词
            pq.OrderBy("student.FAddTime desc");

            //分页指定 Skip: 当前页，Take :每页数量
            pq.Skip(1).Take(10);

            var dt = pq.ToDataTable(); //获取数据

            var studentscount = pq.Count(); //获取当前条件下的数量

            return dt.ToListModel<TScoreSearchDto>(); //ToList<T>() DataTable-->List<T> 的模型转换

            #endregion

        }

上面的示例代码备注图：